Mobile base



FIG. 1 is an isometric view of a mobile base of our new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view there;

FIG. 4 is a rear view thereof;

FIG. 5 a front view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the Figures are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a mobile base, as shown and described. 